Evidence that regular physical activity and a healthy diet prevent/treat illness and prolong life is overwhelming, yet the majority of Americans do neither. Achieving and maintaining behavior change remains a major challenge. Investigators with different theoretical orientations and expertise have designed this application to test two model- derived interventions, addressing unhealthy nutrition practices and sedentary lifestyles. The models are based on Social Learning Theory (Model 1) and the Transtheoretical Model (Model 2). Model 1 s intervention is social unit based, with all members participating together. It capitalizes on vicarious experiences, shared behavioral norms and peer influences. The Transtheoretical Model intervenes with the individual. It recognizes the dynamic nature and individual differences in the change process and defines stage of change, tailoring each interaction accordingly. Progress from the defined stage is enhanced by use of motivational theory. Fire fighters will be the participants in the study. They have a concentration of the harmful behaviors and health risks afflicting the US population, and their unique work schedules makes them ideal for both interventions. The investigators believe that the established relationship they have with firefighters should facilitate recruitment and participation, while reducing attrition. The study s primary outcomes are increased physical activity and aerobic fitness, reduced percent calories as fat, increased servings of fruit ad vegetables and normalized percent body fat. A pilot study of interventions and research process will be conducted in year one. The full outcome trial will be conducted in years two-to-four. In the full trial, firefighters from 36 stations (20-2 subjects per station) will be randomly assigned by station to 1 of 3 conditions: Model 1, Model 2, or usual practice control. Model 1 will be 11, 45-minute peer facilitated group meetings, with 5, 45-minute booster meetings the following year. Peer facilitators will be trained and use scripted lesson plans. Model 2 will use an initial physician visit, 6 health educator meetings and 18, bi-weekly follow-up phone calls. Five, 45-minute additional health educator meetings will occur the following year. The Models contact times are the same, and indices assessed are the same for all three conditions. Evaluation will occur pre- intervention and annually, with quarterly determination of the stage of change for each targeted behavior. Annual measures include maximum oxygen uptake; dietary surveys; body fat percent and distribution; indices of strength, flexibility, spine health and self-reported physical activity; and a questionnaire assessing theoretical constructs and mediating variables. During year 4, no interventions will occur, although subjects will continue to be assessed. Program implementation and fidelity will be monitored for both models, using direct observation and audio taping. Outcomes will be assessed hierarchical linear modeling, including latent and added growth models, which are appropriate for the nested subjects and repeated measures design. Investigators will identify relationships among mediators, the intervention and outcome measures. The study will compare the two health promotion paradigms and provide an understanding of how, and under what conditions behavior change can occur and be maintained.